More CL libs on Github

Recently I made available some GP code I had in Common Lisp (see previous post). Today I also put on my github account the library I did for Ant Colony Optimzation (cl-aco) and a few others like parsers for MKP and QAP, but also a very basic CFFI bindings for libLBFGS. Like before, these are mostly not to get lost since I’m not using/developing  them anymore. But if someone finds this useful in any way, that’s great!

GP code on Github

Some time ago I got an email asking for the code of one of my old papers. Unfortunately the code was lost. But that reminded me that I still had some other code that could actually be made available. Essentially, some Genetic Programming (GP) libraries that I did around seven years ago (which in turn started on some other old code that I had done before).

Fast foward some weeks and it’s now available on my github account these two GP libraries:

  • mini-gp: a minimalistic library that only allows simple tree-based GP
  • core-gp: a larger library that does GP, STGP, GE and GAs.

The code is released as is and it’s not even re-tested. Basically it’s there not to be lost in some old external hard drive. Still, it might be useful to someone who has some interested in GP and Common Lisp. The code it’s not particulary nice in some aspects and it even contains some over-engineering parts, but it’s was fun to do it and back then was very useful to me.

PS: I still have another library for Ant Colony Optimization that I would like to put it on Github too but it still requires a little clean-up. Hopefully in the near future it’s done.

ELS2014: Proceedings, Videos and Slides

The organizers of this year’s European Lisp Symposium made available all the videos of the talks with the respective slides, as well as the PDF containing all the accepted papers.

This is really great and everyone involved in making this happening should be congratulated! For everyone that didn’t attend (like me) it’s a good opportunity to see what happened at ELS. Even though the talks, discussions and networking between participants is the most valuable thing while attending a conference, this is very nice for everyone who was not able to be there.

Once again, kudos to the organizers!

Articles about using F# to implement Lisp

I was looking for examples of Lisp implementations using F# and found these 3 interesting series of blog posts. You can find other posts about implementing Lisp or Scheme using F# but these were the ones I found more comprehensive and different enough to compare different implementations. Although these Lisp implementations are learning experiments and not for production use, it’s fun to see how they are implemented. The series are the following ones:

Tim Robinson’s Lisp Compiler in F#:

  1. Introduction
  2. Parsing with fslex and fsyacc
  3. Expression trees and .NET methods
  4. http://www.partario.com/blog/2009/06/lisp-compiler-in-f-il-generation.html
  5. What’s next?

Ashley Nathan Feniello’s FScheme series:

  1. Scheme in F#
  2. Just ‘let’ Me Be Already!
  3. Lambda the Ultimate!
  4. Rinse and Recurse
  5. What ‘letrec’ Can’t Do
  6. What’s Lisp Without Lists?!
  7. No Wait, Macro the Ultimate!
  8. Oh, The Humanity!
  9. Language vs. Library
  10. Turning Your Brain Inside Out with Continuations
  11. Playing Dice with the Universe
  12. Functional I/O (or at least “O”)
  13. Functional I/O (including “I” this time)
  14. Functional I/O (Historical Debugging)

Luca Bolognese’s Write Yourself a Scheme in 48 Hours in F#:

  1. Part I
  2. Part II
  3. Part III
  4. Part IV
  5. Part V
  6. Part VI
  7. Part VII

Common Lisp on .NET ?

For the past months I have spent most of my time on .NET using C# but I also would have liked to use Common Lisp on it. I do not know of a CL implementation for .NET and I read some time ago that probably doing one is not that easy, as this answer in Stack Overflow states. I wonder if it is related to floating-point exceptions (if someone knowledgeable in this area would like to comment, I thank you in advance!).

Anyway, I decided to look more carefully to see if I could find something and discovered four projects. Initially I was a bit excited that probably there is something after all. But after a more careful observation, they are far from what you would expect or want. For future reference:

The first project, ClearLisp, looked promising but it’s not even CL. Looking at the documentation you realize some differences between it and CL. Also, the project shows no sign of life since 2008 and after playing with it a little bit, it’s far from a modern CL implementation. The second one is not a proper implementation since it’s using ABCL and IKVM. The third one seems to be a way to connect ECL to .NET and uses it as a scripting language. The fourth one also looks more like an attempt than a real implementation (I didn’t explore it).

In the end, there is really no CL implementation for .NET or even one that compiles to bytecode. There is RDNZL which lets you call .NET libraries from a Common Lisp application. However, it’s not the same as having a real implementation.

Furthermore, the state of Lisp-languages on .NET is not much better since you can find lots of half-baked, abandoned languages/implementations or just without real followers (for example, L#, Yarr, dotlisp, Common Larceny, ayaka and others). The major exceptions are probably IronScheme and Clojure. And even the CLR Clojure implementation is just playing catch-up with the Java one.

The set of programmers interested in CL (or even just Lisp) and .NET is probably extremely small and thus, the current state of affairs. However, I feel that this can still be a good area of opportunity if done right.

Edit 1: zvrba on reddit explains the floats issue, which I put here:

The problem with CLR floating-point is that the virtual machine supports only one floating-point type, double (64-bit). (32-bit) float is a storage format only, so in some cases double rounding occurs, leading to results that differ from “proper” float calculations by 1 ulp.

Edit 2: clausb also on reddit pointed out to a list of Lisp projects on .NET he compiled before.

Disclaimer: the views and opinions expressed on this blog are my own and not those of my employer.